Let Flash join and be controlled by media session

content/browser/media/pepper/pepper_web_contents_observer.cc

Index: content/browser/media/pepper/pepper_web_contents_observer.cc
diff --git a/content/browser/media/pepper/pepper_web_contents_observer.cc b/content/browser/media/pepper/pepper_web_contents_observer.cc
new file mode 100644
index 0000000000000000000000000000000000000000..38d0fc495586509744192d10f84febc46220bf19
--- /dev/null
+++ b/content/browser/media/pepper/pepper_web_contents_observer.cc
@@ -0,0 +1,74 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "content/browser/media/pepper/pepper_web_contents_observer.h"
+
+#include "base/feature_list.h"
+#include "base/logging.h"
+#include "content/browser/media/pepper/pepper_player_delegate.h"
+#include "content/browser/media/session/media_session.h"
+#include "content/common/frame_messages.h"
+#include "ipc/ipc_message_macros.h"
+#include "media/base/media_switches.h"
+
+namespace content {
+
+PepperWebContentsObserver::PepperWebContentsObserver(WebContents *web_contents)
+    : WebContentsObserver(web_contents),
+      media_session_(MediaSession::Get(web_contents)) {}
+
+PepperWebContentsObserver::~PepperWebContentsObserver() {
+}

[mlamouri (slow - plz ping), 2016/06/23 13:23:20]

`= default;` instead of `{}`.

[Zhiqiang Zhang (Slow), 2016/06/24 17:43:20]

Done.

+
+void PepperWebContentsObserver::WebContentsDestroyed() {
+  for (auto& instance_player : players_map_) {
+    OnPepperStopsPlayback(instance_player.first);
+  }
+}
+
+void PepperWebContentsObserver::PepperInstanceCreated(int32_t pp_instance) {
+  DCHECK_EQ(players_map_.count(pp_instance), 0u);
+  players_map_[pp_instance].reset(new PepperPlayerDelegate(this, pp_instance));
+}
+
+void PepperWebContentsObserver::PepperInstanceDeleted(int32_t pp_instance) {
+  DCHECK_EQ(players_map_.count(pp_instance), 1u);
+  OnPepperStopsPlayback(pp_instance);
+  players_map_.erase(pp_instance);
+}
+
+bool PepperWebContentsObserver::OnMessageReceived(
+    const IPC::Message& msg, RenderFrameHost* render_frame_host) {
+  if (!base::FeatureList::IsEnabled(media::kFlashJoinsMediaSession))
+    return true;
+  bool handled = true;

[mlamouri (slow - plz ping), 2016/06/23 13:23:20]

style: add an empty line :)

[Zhiqiang Zhang (Slow), 2016/06/24 17:43:20]

Done.

+  IPC_BEGIN_MESSAGE_MAP_WITH_PARAM(PepperWebContentsObserver, msg,
+                                   render_frame_host)
+      IPC_MESSAGE_HANDLER(FrameHostMsg_PepperStartsPlayback,
+                          OnPepperStartsPlayback)
+      IPC_MESSAGE_HANDLER(FrameHostMsg_PepperStopsPlayback,
+                          OnPepperStopsPlayback)
+      IPC_MESSAGE_UNHANDLED(handled = false)
+  IPC_END_MESSAGE_MAP()
+  return handled;

[mlamouri (slow - plz ping), 2016/06/23 13:23:20]

... here too :)

[Zhiqiang Zhang (Slow), 2016/06/24 17:43:20]

Done.

+}
+
+void PepperWebContentsObserver::OnPepperStartsPlayback(int32_t pp_instance) {
+  // TODO(zqzhang): a pepper instance can start playback multiple times. Since
+  // we cannot trully control pepper playback, it may starts to play at any time
+  // interrupting other players.  Working on a variation such that pepper only
+  // gains audio focus at the first time it starts playback, duck it whenever
+  // another player starts playback, and unduck pepper when no other players are
+  // playing.
+  DCHECK_EQ(players_map_.count(pp_instance), 1u);
+  media_session_->AddPlayer(players_map_[pp_instance].get(), 0,
+                                               MediaSession::Type::Content);
+  players_map_[pp_instance]->OnSetVolume(0, 1.0f);
+}
+
+void PepperWebContentsObserver::OnPepperStopsPlayback(int32_t pp_instance) {
+  if (!players_map_.count(pp_instance)) return;

[mlamouri (slow - plz ping), 2016/06/23 13:23:20]

style: return needs to go on a new line.

[Zhiqiang Zhang (Slow), 2016/06/24 17:43:20]

Done.

+  media_session_->RemovePlayer(players_map_[pp_instance].get(), 0);
+}
+}

[mlamouri (slow - plz ping), 2016/06/23 13:23:20]

style: add empty line above and "  // namespace content"

[Zhiqiang Zhang (Slow), 2016/06/24 17:43:20]

Done.